Various approaches have been proposed for effectively allowing the closure of pipe insulation by means of a closing tape attached to the pipe insulation adjacent a radial cut in the pipe insulation. One such structure is shown in U.S. Pat. No. 4,584,217. In this case, a solvent-based adhesive tape has been applied to the pipe insulation and effectively closes the cut by bridging the pipe insulation on either side of the cut. The adhesive must also overcome the tendency of a pipe located interior to the insulation spreading the cut. Other arrangements have made use of an adhesive which adheres to the opposed faces of the cut, such that when the pipe insulation is pushed together to close the cut, the opposed faces adhesively engage and maintain the closed position.
The closure of pipe insulation is difficult, in that typically the pipe insulation is extruded using a foamed polyethylene type material and, thus, the opposed faces of the cut are through the cell structure and adhesion to these surfaces is somewhat difficult when a preformed adhesive layer is applied to the surface. A tape secured to the outer skin of the pipe insulation is also difficult to secure due to poor adhesion with the extruded skin of the article and ready exposure to the elements.
Another problem is with respect to the ability to apply the tape to the pipe insulation in an effective manner. The product, when initially extruded, is of a certain diameter and length, and for a period of at least about 24 hours after extrusion, the product will continue to shrink. Shrinkage is typically in the order of 2%. It has therefore been the practice to produce the pipe insulation by extrusion, cut or partially cut the material to form a longitudinal slit, cut the extruded product to length and thereafter store the material for a length of time sufficient to allow the product to shrink. After shrinkage has occurred, a closing tape is applied to the article adjacent the longitudinal slit. Unfortunately, this results in a two stage process with the tape being applied to the article only after the article has been stored for a certain period of time. It is certainly preferable to apply a tape when the pipe insulation is being produced, but application of the tape at this time will result in wrinkling of the tape, possible poor adhesion of the tape to the product, and the appearance of an inferior product.